[PATCH v3 2/9] Disallow diffopt.close_file when using the log_tree machinery

[Johannes Schindelin <johannes.schindelin@gmx.de>]

We are about to teach the log_tree machinery to reuse the diffopt.file
setting to output to a file stream different from stdout.

This means that builtin am can no longer ask the diff machinery to
close the file when actually calling the log_tree machinery (which
wants to flush the very same file stream that would then already be
closed).

To stave off similar problems in the future, report it as a bug if
log_tree_commit() is called with a non-zero diffopt.close_file.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 builtin/am.c | 6 ++++--
 log-tree.c   | 3 +++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/builtin/am.c b/builtin/am.c
index 0e28a62..47d78aa 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1437,6 +1437,7 @@ static int write_commit_patch(const struct am_state *state, struct commit *commi
 {
 	struct rev_info rev_info;
 	FILE *fp;
+	int res;
 
 	fp = fopen(am_path(state, "patch"), "w");
 	if (!fp)
@@ -1453,10 +1454,11 @@ static int write_commit_patch(const struct am_state *state, struct commit *commi
 	DIFF_OPT_SET(&rev_info.diffopt, FULL_INDEX);
 	rev_info.diffopt.use_color = 0;
 	rev_info.diffopt.file = fp;
-	rev_info.diffopt.close_file = 1;
 	add_pending_object(&rev_info, &commit->object, "");
 	diff_setup_done(&rev_info.diffopt);
-	return log_tree_commit(&rev_info, commit);
+	res = log_tree_commit(&rev_info, commit);
+	fclose(fp);
+	return res;
 }
 
 /**
diff --git a/log-tree.c b/log-tree.c
index 78a5381..dc0180d 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -864,6 +864,9 @@ int log_tree_commit(struct rev_info *opt, struct commit *commit)
 	struct log_info log;
 	int shown;
 
+	if (opt->diffopt.close_file)
+		die("BUG: close_file is incompatible with log_tree_commit()");
+
 	log.commit = commit;
 	log.parent = NULL;
 	opt->loginfo = &log;
-- 
2.9.0.118.g0e1a633